Effects of smoking on bronchial clearance of technetium-99m-DTPA and indium-113m-DTPA.

Abstract

In asymptomatic smokers, epithelial permeability in the distal lung regions is increased. To date, the effect of smoking on the epithelial permeability in proximal lung regions is still debated. The measurement of bronchial clearance of inhaled radiolabeled diethylene-triaminepentaacetic acid (BC-DTPA) can be used to assess epithelial permeability of proximal bronchi, but there are two potential limitations to this method: in vivo breakdown of 99mTc-DTPA in smokers and mucociliary transport of DTPA. Eight nonsmokers and eight asymptomatic smokers were studied. We used a spinning disk system to generate an aerosol of large particles of 99mTc-DTPA or 113mIn-DTPA (MMAD 6.3 microns). To measure the bronchial clearance of 99mTc-DTPA and 113mIn-DTPA, we analyzed the perihilar regions of the lung. To determine the contribution of mucociliary transport, we measured the activity over a tracheal region of interest (ROI) in eight nonsmokers. Technetium-99m-DTPA bronchial clearance did not differ in smokers (1.16 +/- 0.54%/min; mean +/- s.d.) or nonsmokers (1.29 +/- 0.51%/min; ns). The 113mIn-DTPA bronchial clearances in nonsmokers (1.24 +/- 0.51%/min) and in smokers (1.01 +/- 0.66%/min) were similar to the 99mTc-DTPA bronchial clearances (ns). In the tracheal ROI, we found no increase in activity. In smokers, BC-DTPA was not increased compared to nonsmokers. In contrast to distal lung regions, there was no evidence of breakdown of the 99mTc-DTPA complex in the proximal regions of smokers' lungs. Mucociliary clearance does not significantly contribute to BC-DTPA.